Technical Abstract:
Previous research has shown that flumioxazin has the potential to cause peanut injury. In response to this concern, laboratory experiments were conducted to investigate the influence of temperature on flumioxazin-treated peanut seed germination. Also, greenhouse experiments investigated the influence of six different irrigation intervals after soil-applied flumioxazin preemergence (PRE) application on peanut emergence and injury. Laboratory experiments utilizing 14C-flumioxazin were also conducted to investigate differential tolerances exhibited by peanut, ivyleaf morningglory, and sicklepod to flumioxazin. Flumioxazin treatments containing either water dispersible granular (WDG) or wettable powder (WP) formulation at 1.4 mol/L did not influence germination compared to non-treated peanut across all temperature regimes. Peanut treated with a WDG or a WP formulation of flumioxazin PRE and receiving irrigation at emergence and at 2 and 4 d after emergence were injured between 40 and 60%, while peanut treated at 8 and 12 d after emergence were injured between 25 and 15%, respectively. Total 14C absorbed by ivyleaf mornigglory was 57% of applied while sicklepod absorbed 46%, at 72 hours after treatment (HAT). Peanut absorbed 74% of applied 14C 72 HAT. A majority of absorbed 14C remained in roots for sicklepod, ivyleaf morningglory, and peanut at all harvest times. Ivyleaf morningglory contained 41% of the parent herbicide 72 HAT while sicklepod and peanut contained only 24 and 11% parent compound, respectively. Regression slopes indicated slower metabolism by ivyleaf morningglory compared to sicklepod and peanut.